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\DOI{10.5802/crchim.387}
\datereceived{2024-07-24}
\daterevised{2024-11-10}
\datererevised{2025-01-27}
\dateaccepted{2025-02-20}
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%%%Copyeditor : Reeja

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\dateposted{2025-03-12}
\begin{document}

\begin{noXML}

\CDRsetmeta{articletype}{research-article}

\title{Exploring temperature-dependent properties in advanced graphene
oxide nanocomposites for enhanced energy applications}

\alttitle{Exploration des propri\'{e}t\'{e}s d\'{e}pendant de la
temp\'{e}rature dans les nanocomposites avanc\'{e}s \`{a} base d'oxyde
de graph\`{e}ne pour des applications \'{e}nerg\'{e}tiques
am\'{e}lior\'{e}es}

\author{\firstname{Manal Ahmed} \lastname{Awad}\CDRorcid{0000-0002-5294-1721}\IsCorresp} 
\address{King Abdullah Institute for Nanotechnology, King Saud
University, PO Box 2455, Riyadh 11451, Saudi Arabia} 
\email[M. A. Awad]{mawad@ksu.edu.sa}

\author{\firstname{Khalid Mustafa} \lastname{Ortashi}\CDRorcid{0000-0002-4030-1583}}
\address{Department of Chemical Engineering, King Saud University, PO
Box 800, Riyadh 11421, Saudi Arabia}

\author{\firstname{Hayat} \lastname{Althobaiti}}
\address{Department of Physics and Astronomy, College of Sciences,
King Saud University, Riyadh 11451, Saudi Arabia}

\author{\firstname{Nada\nobreakauthor Mohammed} \lastname{Merghani}\CDRorcid{0000-0003-0934-1699}\IsCorresp}
\address{Central Research Laboratory, King Saud University, PO Box
11451, Riyadh, Saudi Arabia}
\email[N. M. Merghani]{nmerghani@KSU.EDU.SA}

\keywords{\kwd{Graphene 
oxide}\kwd{Biopolymers}\kwd{Characterization}\kwd{Electric 
properties}\kwd{Energy}}

\altkeywords{\kwd{Oxyde de 
graph\`{e}ne}\kwd{Biopolym\`{e}res}\kwd{Caract\'{e}risation}\kwd{Propri\'{e}t\'{e}s 
\'{e}lectriques}\kwd{\'{E}nergie}}

\thanks{King Saud University, Saudi Arabia (RICSP-25-3)}

\begin{abstract}
This article provides a comprehensive overview of recent advancements
in the production of graphene-based biopolymer nanocomposites,
which have garnered significant attention due to their remarkable properties.
By adding graphene oxide (GO) to a biopolymer matrix 
(biopolymer composite [bioC]), we
successfully synthesized high-performance bioC--GO nanocomposites and
conducted a thorough investigation of their electrical and thermal
characteristics.
The nanocomposites were structurally characterized
using analytical techniques such as transmission electron microscopy
(TEM), scanning electron microscopy (SEM), energy-dispersive X-ray
spectroscopy (EDS), X-ray diffraction (XRD), and thermogravimetric
analysis (TGA). The XRD revealed the amorphous nature of bioC while
bioC--GO nanocomposites exhibited distinctive peaks attributed to
interactions among fish scales, GO, and the biopolymer matrix. 
Both SEM and EDS confirmed a uniform distribution of biopolymers on GO, with
elemental analysis indicating slight variations in carbon and oxygen
content due to functionalized GO. The TEM revealed nanostructured bioC--GO
flakes with wrinkled morphology. The TGA demonstrated the enhanced thermal
stability of bioC--GO nanocomposites withstanding temperatures up to 
800 \textdegree{}C, attributed to covalent interactions between collagen and
nanographene oxide. Likewise, we investigated the resistivity response
of bioC--GO nanocomposites under forward and reverse bias at various
bias voltages at room temperature. The resistivity values, which are
inversely proportional to conductivity, were found to be very low for
the bioC--GO nanocomposites when exposed to temperatures as high as
150 \textdegree{}C at a steady applied voltage of 5 V. These findings
demonstrate the potential of bioC--GO nanocomposites for applications
requiring superior thermal stability, electrical conductivity, and
environmentally friendly materials.
\end{abstract}

\begin{altabstract}
Cet article donne un aper\c{c}u complet des avanc\'{e}es r\'{e}centes
dans la production de nanocomposites de biopolym\`{e}res \`{a} base de
graph\`{e}ne, qui ont suscit\'{e} une grande attention en raison de
leurs propri\'{e}t\'{e}s remarquables. En ajoutant de l'oxyde de
graph\`{e}ne (GO) \`{a} une matrice de biopolym\`{e}res (bioC), nous
avons synth\'{e}tis\'{e} avec succ\`{e}s des nanocomposites bioC--GO de
haute performance et men\'{e} une \'{e}tude approfondie de leurs
caract\'{e}ristiques \'{e}lectriques et thermiques. Les nanocomposites
ont \'{e}t\'{e} caract\'{e}ris\'{e}s structurellement \`{a} l'aide de
techniques analytiques telles que la microscopie \'{e}lectronique \`{a}
transmission (TEM), la microscopie \'{e}lectronique \`{a} balayage
(SEM), la spectroscopie X \`{a} dispersion d'\'{e}nergie (EDS), la
diffraction des rayons X (XRD) et l'analyse gravim\'{e}trique thermique
(TGA). La DRX a r\'{e}v\'{e}l\'{e} la nature amorphe du bioC, tandis
que les nanocomposites bioC--GO pr\'{e}sentaient des pics distinctifs
attribu\'{e}s aux interactions entre les \'{e}cailles de poisson, le GO
et la matrice biopolym\`{e}re. Le MEB et l'EDS ont confirm\'{e} une
distribution uniforme des biopolym\`{e}res sur le GO, l'analyse
\'{e}l\'{e}mentaire indiquant de l\'{e}g\`{e}res variations dans la
teneur en carbone et en oxyg\`{e}ne dues au GO fonctionnalis\'{e}. Le
MET a r\'{e}v\'{e}l\'{e} des flocons de bioC--GO nanostructur\'{e}s avec
une morphologie pliss\'{e}e. L'ATG a d\'{e}montr\'{e}
l'am\'{e}lioration de la stabilit\'{e} thermique des nanocomposites
bioC--GO \`{a} des temp\'{e}ratures allant jusqu'\`{a} 800 \textdegree{}C,
attribu\'{e}e aux interactions covalentes entre le collag\`{e}ne et
l'oxyde de nanograph\`{e}ne. De m\^{e}me, nous avons \'{e}tudi\'{e} la
r\'{e}ponse de r\'{e}sistivit\'{e} des nanocomposites bioC--GO sous une
polarisation directe et inverse \`{a} diff\'{e}rentes tensions de
polarisation \`{a} temp\'{e}rature ambiante. Les valeurs de
r\'{e}sistivit\'{e}, qui sont inversement proportionnelles \`{a} la
conductivit\'{e}, se sont av\'{e}r\'{e}es tr\`{e}s faibles pour les
nanocomposites bioC--GO lorsqu'ils \'{e}taient expos\'{e}s \`{a} des
temp\'{e}ratures aussi \'{e}lev\'{e}es que 150 \textdegree{}C sous une
tension appliqu\'{e}e constante de 5 V. Ces r\'{e}sultats d\'{e}montrent
le potentiel des nanocomposites bioC--GO pour les applications
n\'{e}cessitant une stabilit\'{e} thermique sup\'{e}rieure, une
conductivit\'{e} \'{e}lectrique et des mat\'{e}riaux respectueux de
l'environnement.
\end{altabstract}

\shortrunauthors

\maketitle

\twocolumngrid

\end{noXML}

\section{Introduction}\label{sec1}

Over the past two decades, nanoscience has undergone explosive
growth with miniaturization becoming increasingly important in fields
such as computing, sensing, and biomedicine. This tendency is expected
to significantly improve the already \mbox{excellent} reputation of
nanotechnology. To advance these domains, it is crucial to be able to
successfully synthesize nanoparticles of different materials, sizes,
and forms and to put them together into intricate
structures~\cite{1,2,3}. The unique structural \mbox{properties} of
nanoparticles have recently led to a wide range of applications.
Meanwhile, scientists are concentrating on materials with superior
physicochemical properties that make them more appropriate for
nanoscience and technology. Graphene and its polymer nanocomposites are
among these materials that have had a major influence on nanoscience
and hence on contemporary technology and scientific study. Because of
its numerous beneficial qualities, scientists and engineers have long
been fascinated by carbon. Graphene, a unique form of carbon,
consists of a two-dimensional arrangement of 
sp$^2$-bonded carbon atoms in
a hexagonal lattice~\cite{4}. The remarkable surface area, mechanical
strength, photocatalytic qualities, electrical and thermal
conductivity, and antibacterial properties of graphene oxide (GO) make it a
very sought-after \mbox{material}~\cite{5}. Known for its honeycomb structure
of nanoscale sheets of sp$^2$ carbon atoms, GO exhibits
impressive molecular barrier capabilities, electrical conductivity, and
mechanical strength among other advantageous features. Because of
these characteristics, several research projects have focused on
creating polymer-based nanocomposites that include graphene~\cite{6}.
Graphene oxide's versatility extends to its role in composite
materials, where it improves properties such as lubrication, thermal
conductivity, and \mbox{mechanical} strength~\cite{7}. 


As environmental concerns grow, there is increasing interest in
biopolymer mixtures and nanocomposites as sustainable
alternatives~\cite{8}. In several industries such as packaging,
agriculture, and medicine, biopolymers made from renewable resources
have more advantages than their petroleum-based equivalents~\cite{9}.
Recently, there has been a lot of interest in GO as a
possible component for 2D nanomaterials that resemble graphene. Graphene oxide
typically has a carbon-to-oxygen atomic \mbox{ratio} of between 2:1 and 3:1
and comprises a carbon framework modified with residual
oxygen-containing groups. These materials exhibit unique chemical and
physical properties, including high electrical conductivity, a tunable
degree of \mbox{functionalization,} and a large surface area, making them
attractive for various applications~\cite{10,11}. The improvement of GO
preparation methods and the exploration of its potential applications
have been the focus of extensive experimental\break research. 

Recently, there has been a surge in research on nanocomposites that
integrate GO with polymers and inorganic
nanoparticles~\cite{12}. For instance, red seaweed is the source of
carrageenan, a biopolymer with special qualities for a range of uses.
Kappa-carrageenan (KC) is a common thickening agent in the food industry because
of its gelling properties~\cite{13}. Its counterpart iota-carrageenan (IC) is
a water-soluble, biodegradable polymer, making it suitable for a
variety of applications \mbox{including} as a host matrix in this study. The
synergy between inorganic components and organic polymers is \mbox{driving}
innovation in materials science. The mechanical, thermal, and
electrical properties of graphene-based polymer nanocomposites are
better than those of new polymers and traditional filler-based
\mbox{composites}~\cite{14}. Because of their many uses, GO and polymer
composites have attracted a lot of interest from a variety of industries,
such as high-strength materials, catalysts, energy-related systems, and
\mbox{energy} storage and conversion devices. Revolutionary breakthroughs in
materials science and technology are anticipated because of the
exceptional qualities of GO and the adaptability of polymer
\mbox{matrices}~\cite{15}.

This study aims to synthesize and evaluate novel 
biopolymer composite (bioC)--GO nanocomposites
by incorporating a mixture of fish scale powder, KC, and
IC into GO. The research explores the potential
of these materials to develop advanced \mbox{composites} with enhanced thermal
and electrical properties, such as resistivity, heat stability, and
breakdown strength. To the best of our knowledge, this is the first
time this unique combination of biopolymers and GO has been
utilized, offering promising insights into the development of
multifunctional materials for diverse applications.

\begin{figure*}
{\vspace*{-2pt}}
\includegraphics{fig01}
{\vspace*{-2pt}}
\caption{\label{fig1}Schematic illustration of the synthesis process of
bioC--GO nanocomposites.}
{\vspace*{-3pt}}
\end{figure*}

\section{Materials and methods}

\subsection{Preparation of fish scale powder}

Biowaste Tilapia fish scales (FS) were sourced from the local fish
market in Riyadh, Saudi \mbox{Arabia}. The~scales were thoroughly cleaned,
first being rinsed with tap water to get rid of any surface dirt and
tissues that could have stuck. The cleanliness of the scales was
then guaranteed by carefully removing any unnecessary elements. After
that, the scales were carefully cleaned with deionized water to get rid
of any remaining contaminants. The cleaned fish scales were sun-dried
until they were crisp and brittle to maintain quality and avoid
microbial contamination. To improve use, the scales were coarsely
crushed into a powder after drying. To guarantee uniformity of the
finished product, the powdered fish scales were then sieved to remove
big particles and obtain consistent particle size. Then,
15--50~ml of a boiling mixture of ethanol and deionized
water (1:9~v/v) was used to dissolve 30--75~mg of finely
powdered fish scales. The mixture was stored at
4~\textdegree{}C until it was needed again, guaranteeing its preservation
and preparedness for further research.

\subsection{Preparation of bioC--GO nanocomposites}\label{sec2.2}

We procured GO, KC, and
IC from Sigma-Aldrich for our experimental
investigations. Fish scale powder (30~mg) from biowaste sources was
dissolved in boiling ethanol and deionized water. Then, 100 mg of
IC and 30 mg of KC were combined with 20 ml
of the biowaste solution, and the combination of 
bioC was stirred constantly for 3~h at around 70~\textdegree{}C. A
digital sonicator fitted with a 10~mm diameter probe was used to treat
the final solution, known as bioC--GO, to guarantee complete homogeneity
of the bioC solution and GO dispersions (150~mg). The sonicator was
programmed to run in pulse mode at a frequency of 20~kHz and an
ultrasonic output of 750~W. To keep the level of the solutions constant
during the sonication procedure, the sample beakers were carefully
positioned in a water bath. 
After sonicating the solutions, we dried
them for 24~h at 35~\textdegree{}C using the evaporative-casting
procedure.  The mixes were then transferred to Petri dishes. This
procedure made it easier for the solutions to form films (see
Figure~\ref{fig1}), which allowed for more research and\break testing.


\subsection{Characterization techniques}\label{sec2.3}

The properties of the synthesized bioC and bioC--GO nanocomposites were
investigated using a range of characterization techniques. Using a
Bruker D8 Discover X-ray diffractometer (Billerica, Massachusetts,
USA), the crystalline structure and phase purity were examined
throughout a scanning range of 1\textdegree{}--100\textdegree{}. An
energy-dispersive X-ray spectroscopy (EDS) spectrometer (JSM-2100F, JEOL,
USA) and a  scanning electron microscope
(JSM-7600F, JEOL, USA) were used for morphological and elemental investigations. A drop
of the sonicated bioC--GO solution was applied to a carbon-coated
conductive tape for scanning electron microscopy (SEM) and EDS measurements, and it was let to dry
under a light before examination. A thermogravimetric analysis (TGA)
(TGA/DSC 1) analyzer (Mettler Toledo, Columbus, USA) was used to
evaluate thermal stability and breakdown. Nitrogen flow at a rate of
10~\textdegree{}C/min was used to evaluate around 10 mg of the dried produced
film throughout a temperature range of 0--800~\textdegree{}C. The resulting
thermograms illustrate weight loss and heat flow as a function of
temperature. The electrical resistance of the films was assessed by
measuring temperature-dependent current--voltage (I--V) characteristics.
A digital multimeter and waveform generator were used for these tests,
which were carried out in a temperature-controlled setting.

\section{Results and discussion} \label{sec3}

Figure~\ref{fig2}A shows the X-ray diffraction (XRD) pattern of bioC
characterized by broader and less intense peaks, indicative of its
amorphous nature. In contrast, Figure~\ref{fig2}B illustrates the distinctive
XRD peaks of the bioC--GO nanocomposites observed at 2${\uptheta}$
angles of 20\textdegree{}, 27\textdegree{}, 42\textdegree{}, 49\textdegree{},
73\textdegree{}, and 89\textdegree{}. These peaks reflect the structural
contributions of fish scales, GO, and the KC--IC/FS
(bioC) biopolymer matrix. The XRD pattern of pure gelatin powder
exhibits a broad peak at $2{\theta} \approx 20\text{\textdegree}$,
consistent with its semi-crystalline nature and triple-helical
structure~\cite{16,17}. The reduced intensity of the peak at
42\textdegree{} suggests graphene exfoliation within the bioC matrix,
significantly altering the crystalline structure of 
GO~\cite{18}. Peaks at 42\textdegree{} and 49\textdegree{}, previously
attributed to pure KC and IC~\cite{18,19,20}, show
diminished intensity in the bioC--GO nanocomposites, indicating
modifications in the crystalline arrangement of these components. These
findings provide valuable insights into the structural evolution of
bioC--GO nanocomposites, underscoring the dynamic interactions between
the biopolymer matrix and GO.


\begin{figure}
\includegraphics{fig02}
\caption{\label{fig2}XRD patterns of (A) bioC film and (B) bioC--GO
nanocomposite.}
\end{figure}


\begin{figure*}
{\vspace*{-2pt}}
\includegraphics{fig03}
{\vspace*{-2pt}}
\caption{\label{fig3}BioC film: (A) SEM image, (B) EDS patterns and
a tabulation of the EDS spectrum; bioC--GO nanocomposites: (C) 
SEM image, (D) EDS patterns and a tabulation of the EDS spectrum.}
{\vspace*{-3pt}}
\end{figure*}


In Figure~\ref{fig3}A,
the SEM image shows that the bioC sample
exhibits a compact and dense structure with a slightly flaky surface.
The corresponding EDS spectrum (Figure~\ref{fig3}B)
confirms the presence of elements such
as C, O, Na, Mg, S, Cl, K, Ca, and Fe, with the weight\% of carbon
measured as 30.44\%. In contrast, Figure~\ref{fig3}C reveals the
morphology of the bioC--GO nanocomposites characterized by wrinkly
surfaces resulting from the synthesis process. The SEM image
demonstrates that the biopolymers uniformly cover the 
GO substrate. Figure~\ref{fig3}D displays the EDS spectrum for the
nanocomposite, identifying elements including C, O, Na, Mg, Si, S, Cl,
K, and Ca, which are attributed to the utilized substrate and
incorporated materials~\cite{21}. From the tabulated data in
Figure~\ref{fig3}C, the carbon weight\% in the bioC--GO nanocomposites
is estimated as 28.34\%, slightly lower than that of the bioC sample.
Phiri et~al.~reported that functionalized GO can introduce
oxygen-containing functional groups, which slightly increase the oxygen
weight\% in the composite~\cite{22}. These findings provide insights
into the \mbox{elemental} composition and distribution within the bioC--GO
nanocomposites, offering valuable information about their structural
characteristics and potential applications~\cite{23,24}.

\begin{figure*}
\includegraphics{fig04}
\caption{\label{fig4}(A, B) TEM images with scale bars 
50~nm and 200~nm, respectively.}
\end{figure*}



Transmission
electron microscopy (TEM) was used to assess the bioC--GO
nanocomposite ink's morphology as shown in Figures~\ref{fig4}A and B.
Imaging using TEM revealed the
presence of nanocomposite flakes with one or more layers. Although GO
is primarily clear, its surface frequently exhibits brightness changes
due to elastic corrugations and scrolled or folded edges~\cite{25}. The
TEM images revealed bioC--GO sheets that were extensively wrinkled,
highlighting their distinct structural characteristics. After careful
TEM investigation, it was determined that our samples' diameters fall
within the nanometer range, highlighting their nanostructured
nature~\cite{26}. Additionally, the samples' high level of disorder
highlights how dynamic and complicated the bioC--GO nanocomposites are.
Consequently, the other components in the composite help widen the
interlayer gap between the GO sheets, preventing them from
reassembling~\cite{27,28}. 


 A thorough TGA of the bioC--GO
nanocomposites was conducted in a nitrogen environment at a heating
rate of 50~\textdegree{}C. The bioC and bioC--GO 
\mbox{nanocomposites} were heated
at a rate of 20~\textdegree{}C per minute from 100~\textdegree{}C to
800~\textdegree{}C. The TGA data displayed in Figures~\ref{fig5}A and
B provide a wealth of information on the thermal characteristics of
the bioC and nanocomposites~\cite{29}. 

\begin{figure*}
\includegraphics{fig05}
\caption{\label{fig5}TGA curves of (A) bioC film and (B) bioC--GO
nanocomposites.}
\end{figure*}


In Figure~\ref{fig5}A, the TGA curve of a
composite made of KC, IC, and fish scale
powder reveals the main thermal decomposition stages of the
bioC. Initially, weight loss occurs between
approximately 50 and 200~\textdegree{}C, which is attributed to the
evaporation of absorbed and bound water due to the hydrophilic nature
of KC, IC, and fish scale powder. A
subsequent weight loss is observed in the range of
200--300~\textdegree{}C, corresponding to the thermal degradation of
carrageenan. This involves the breakdown of glycosidic bonds and the
release of volatile products. Another significant weight loss occurs
between 300 and 450~\textdegree{}C, primarily due to the thermal
decomposition of collagen proteins in the fish scale powder along with
the remaining organic matter from the carrageenan. Beyond
450~\textdegree{}C, additional weight loss is associated with partial
demineralization or \mbox{structural} transformations of mineral components,
such as hydroxyapatite, present in the fish scale powder. At
temperatures exceeding 600~\textdegree{}C, the residual mass consists
predominantly of inorganic material, primarily reflecting the mineral
content of the composite~\cite{30}.

In Figure~\ref{fig5}B, approximately 15--20\% of the total weight loss
in the nanocomposites is attributed to the main chain breakdown, which
begins at 200--250~\textdegree{}C. The bioC--GO nanocomposites are
hypothesized to exhibit significantly higher thermal stability, as they
demonstrate only 45\% weight loss at 800~\textdegree{}C, with complete
combustion not occurring until around 800~\textdegree{}C~\cite{31}.
Interestingly, weight loss due to solvent evaporation is observed at
lower temperatures. Previous research by Pati et~al.~\cite{32} suggests
that the decomposition of graphene nanocomposites occurs in the
temperature range of 200--280~\textdegree{}C. Meanwhile, polymer breakdown
takes place between 350 and 480~\textdegree{}C. According to Tapas Mitra
et~al., collagen-functionalized nanographene oxide (bioC--GO) scaffolds
begin to degrade predominantly after 350~\textdegree{}C. Based on weight
loss rates at 400~\textdegree{}C, 800~\textdegree{}C, and 900~\textdegree{}C,
bioC--GO scaffolds demonstrate far greater thermal stability compared to
native collagen. This enhanced stability is likely due to covalent
interactions between nanographene oxide and collagen~\cite{33}.
Furthermore, 47\% of the amine groups in the bioC--GO scaffold are
involved in intermolecular \mbox{interactions}~\cite{34}. These findings not
only highlight the improved thermal stability of bioC--GO nanocomposites
but also open avenues for further research and potential applications
in various \mbox{industries}~\cite{35}.

\begin{figure}
\includegraphics{fig06}
{\vspace*{-2pt}}
\caption{\label{fig6}(A) Resistivity response under forward
and reverse bias at room temperature and
(B) resistivity change with respect to temperature
for bioC--GO nanocomposites.}
{\vspace*{-2pt}}
\end{figure}

When fish scales are added to GO and
KC or IC composites, the
resulting composite's performance and thermal stability can be improved
over earlier research outcomes~\cite{36,37,38,39,40,41}. According to earlier
research studies, the following are some possible methods for enhancing
thermal stability when fish scales are added. The hierarchical
structure of collagen and mineral layers in fish scales contributes to
their stiffness and flexibility. The resultant composite is more
flexible and less prone to break or distort \mbox{under} stress when the
mechanical rigidity of GO and the gel-like elasticity of carrageenan
are combined. This \mbox{synergy} in mechanical properties also enhances
thermal stability, as a well-integrated composite \mbox{better} resists
thermal expansion and contraction. Likewise,~when the material is
subjected to mechanical or thermal stress, collagen from fish scales
aids in energy dissipation. These characteristics delay structural
collapse by allowing the composite to absorb and transfer energy more
efficiently, resulting in increased thermal stability.  By serving as a
heat sink and \mbox{dispersing} thermal energy throughout the composite
matrix, GO additionally supports this process~\cite{42,43,44,45}.

At room temperature, the resistivity response of the bioC--GO
nanocomposites under forward and \mbox{reverse} bias was examined at different
bias voltages as shown in Figure~\ref{fig6}A. Furthermore, the impact
of temperature on the sample's DC conductivity was investigated using
bias voltages of 5~V up to 150~\textdegree{}C as shown in
Figure~\ref{fig6}B. The resistivity measurements performed can be
fitted by the one-dimensional variable range hopping  model, using
the following formula: 
{\[
\rho _{T}=\rho _{0}\exp \left[\left(\frac{T_{0}}{T}\right)^{\frac{1}{2}}\right]
\]}\unskip
where the sample $T_{0}$ stands for the energy barrier between
localized states. The temperature-dependent behavior of the produced
bioC--GO nanocomposites yielded interesting results. The resistivity
\mbox{values}, which are inversely proportional to conductivity, were found to
be very low for the bioC--GO nanocomposites when exposed to temperatures
as high as 150~\textdegree{}C at a steady applied voltage of 5~V.
Consequently, the conductivity of the nanocomposites showed a
significant increase with rising temperature, highlighting the dynamic
nature of the material's conductivity. Furthermore, the temperature
dependence of the resistivity measurements revealed several noteworthy
patterns~\cite{46,47,48}. At lower temperatures, the localized
electrons lacked sufficient thermal energy to overcome potential
barriers, resulting in the lowest conductivity values. As the
temperature increased, the conduction process \mbox{accelerated,} reaching
maximum efficiency at higher temperatures~\cite{49,50}. The promising
properties of the bioC--GO nanocomposites emphasize their adaptability
and potential for various technological applications, including their use as
cathode materials in batteries and electronic devices~\cite{51}.

\section{Conclusion}\label{sec4}

This study presents the development and characterization of
graphene-based bioC--GO nanocomposites specifically engineered for
applications requiring enhanced thermal stability, electrical
conductivity, and environmentally friendly properties. The structural
and morphological analyses, including TGA, SEM, EDS, TEM, and XRD,
confirmed the uniform dispersion and strong covalent interactions
within the bioC--GO matrix. Our findings demonstrate that the
resistivity values of bioC--GO nanocomposites remain very low even at
temperatures as high as 150~\textdegree{}C at a steady applied
voltage of 5~V. This indicates a significant increase in conductivity with
rising temperature, highlighting the dynamic and thermally responsive
nature of the material. These results indicate that bioC--GO
nanocomposites hold promise as cathode materials for energy storage
systems, such as batteries, and for use in electronic devices requiring
stable conductivity under high-temperature conditions.

\section*{Declaration of interests}
The authors do not work for, advise, own shares in, or receive funds
from any organization that could benefit from this article, and have
declared no affiliations other than their research organizations.

\section*{Acknowledgment}
The authors express their gratitude to the Central Research
Laboratory/Research Institute/Center Supporting Program (RICSP-25-3) under
King Saud University, Saudi Arabia.

\CDRGrant[KSU]{RICSP-25-3}

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